1. Field of the Invention
The present invention relates to electroplating devices, and more particularly to a method for fabricating a thin film transistor array for a liquid crystal display with an electroplated gate or data metal.
2. Description of the Related Art
Displays, such as, liquid crystal displays, have found a wide range of uses in modern electronic equipment. With the improvement of viewing quality and the reduction of viewing angle limitations, liquid crystal displays have become more appealing for a plurality of new applications and well as more desirable for old applications. In many instances, liquid crystal displays are replacing cathode ray tube (CRT) displays. For example, liquid crystal displays are now being employed for computer monitors.
Liquid crystal displays, in many applications, provide desirable features, such as light weight, low profile and low power, to name a few. Due to increased usage of liquid crystal technology, there is a large driving force to reduce the costs of such displays. One way to reduce the costs of liquid crystal displays is to reduce the number of processing steps needed to fabricate these devices. For example, many liquid crystal display thin film transistor TFT arrays are fabricated in processes which include a plurality of masking steps. It would be advantageous to reduce the number of masking, deposition, and etching steps used to build these TFT arrays. The industry is currently moving to five mask processes, but it is desirable to reduce the number further to four mask steps.
Therefore, a need exists for a method for fabricating a TFT array in less than five masking steps. A further need exists for providing a display device produced by this method which includes an electroplated gate or data metal, since metal deposition by electroplating is lower cost then conventionally employed sputtering processes.
An electroplating apparatus, in accordance with the present invention, includes a plurality of chambers. A first chamber includes an anode therein. The first chamber has an opening for delivering an electrolytic solution containing metal ions onto a surface to be electroplated. The surface to be electroplated is preferably a cathode. A second chamber is formed adjacent to the first chamber and has a second opening in proximity of the first opening for removing electrolytic solution containing metal ions from the surface to be electroplated. The plurality of chambers are adapted for movement in a first direction along the surface to be electroplated.
In alternate embodiments, the plurality of chambers may include a rinse chamber including a supply of water for rinsing the surface, and/or a pretreatment chamber which leads the first chamber for pretreating and cleaning the surface to be electroplated. The surface to be electroplated preferably includes conductive lines, although other features may be plated as well. The conductive lines may extend longitudinally along the first direction. The conductive lines preferably connect to a common node. The apparatus may include a plurality of first chambers and a plurality of second chambers. The anode may include a consumable metal anode. The anode may include an inert metal and the electrolyte solution may include ions of a metal to be deposited. The first chamber may be surrounded by the second chamber, for example in a pipe within a pipe arrangement. The pipes may be of any shape, for example circular in cross-section, or rectangular in cross-section or combinations thereof. The second chamber may include a plurality of chamber which surround the first chamber.
A method for forming an electroplated metal on conductive layers, in accordance with the present invention, includes the steps of providing a substrate having elongated conductive structures formed thereon, providing an electroplating apparatus including a plurality of chambers, a first chamber including an anode therein, the first chamber including a first opening for delivering an electrolytic solution containing metal ions onto the conductive structures to be electroplated, the conductive structures being a cathode, and a second chamber formed adjacent to the first chamber and having a second opening in proximity of the first opening for removing electrolytic solution containing metal ions from the conductive structures to be electroplated and moving the plurality of chambers in a first direction along the conductive structures to be electroplated to electroplate the metal onto the conductive structures.
In other methods, the plurality of chambers may include a rinse chamber, and the method may further include the step of rinsing an electroplated surface of the conductive structures. The plurality of chambers may include a pretreatment chamber which leads the first chamber, and the method may further include the steps of pretreating and cleaning the conductive structures to be electroplated. The conductive structures may include gate of data lines for active devices. The conductive structures may extend longitudinally along the first direction. The conductive structures may connect to a common node during electroplating. The electroplating apparatus may include a plurality of first chambers and a plurality of second chambers, and the method may further include the step of incrementally electroplating the conductive structures with each of the plurality of first chambers.
In still other methods, the anode may include a consumable metal anode or the anode may include an inert metal and the electrolyte solution may include ions of a metal to be deposited. The step of providing an electroplating apparatus may include the step of providing the apparatus in which the first chamber is surrounded by the second chamber.
A method for fabricating an active array for a liquid crystal display device, in accordance with the present invention, includes the steps of forming addressing lines for the active array, providing an electroplating apparatus including a plurality of chambers, a first chamber including an anode therein, the first chamber including a first opening for delivering an electrolytic solution containing metal ions onto the addressing lines to be electroplated, the addressing lines being a cathode, and a second chamber formed adjacent to the first chamber and having a second opening in proximity of the first opening for removing electrolytic solution containing metal ions from the addressing lines to be electroplated, and moving the plurality of chambers in a first direction along the addressing lines to be electroplated to electroplate the metal onto the addressing lines.
The addressing lines may include indium tin oxide or indium zinc oxide. The addressing lines may extend longitudinally along the first direction. The addressing lines may connect to a common node during electroplating The methods may further include the steps of forming access devices for accessing pixel electrodes through the addressing lines and forming data lines for addressing the pixel electrodes. The addressing lines may be included in a top gate structure or a bottom gate structure. The method is preferably performed in only four masking steps. The method may further include the step of forming access devices for accessing pixel electrodes through gate lines, where the addressing lines are for addressing the pixel electrodes. The active array may include conductive structures isolated from the cathode such that electroplating is prevented on the conductive structures. The conductive structures may include pixel electrodes.